Miho Kumagai

Effects of ATP on intracellular calcium dynamics of neurons and satellite cells in rat superior cervical ganglia.

Abstract. Adenosine 5′-triphosphate (ATP) which is released from neuronal and non-neuronal tissues interacts with cell surface receptors to produce a broad range of physiological responses. The present study addressed the issue of whether the cells of the superior cervical ganglia (SCG) respond to ATP. To this end, the dynamics of the intracellular calcium ion concentration ([Ca2+]i) of neurons and satellite cells in intact SCG was analyzed by laser scanning confocal microscopy. ATP produced an increase of [Ca2+]i in both neurons and satellite cells; initially, ATP elicited [Ca2+]i increase in satellite cells and, subsequently, a [Ca2+]i change in neurons was observed. P1 purinoceptor agonists had no effect on this process, but P2 purinoceptor agonists induced [Ca2+]i increase and suramin totally inhibited ATP-induced [Ca2+]i dynamics in both neurons and satellite cells. In satellite cells, Ca2+ channel blockers and the removal of extracellular Ca2+, but not thapsigargin pretreatment, abolished ATP-induced [Ca2+]i dynamics. In contrast, thapsigargin pretreatment abolished ATP-induced [Ca2+]i dynamics in neurons. Reactive blue-2 inhibited the ATP-induced reaction on neurons alone. Uridine 5′-triphosphate caused a [Ca2+]i increase in neurons and α,β-methylene ATP caused a [Ca2+]i increase in satellite cells. We concluded that neurons respond to extracellular ATP mainly via P2Y purinoceptors and that satellite cells respond via P2X purinoceptors.

Evaluation of Transcutaneous and End-Tidal Carbon Dioxide During Intravenous Sedation in Volunteers

Objective: During intravenous sedation, end-tidal carbon dioxide (ETCO2) is usually measured with a nasal cannula or mouth-nose cannula. We compared the measurement accuracy of ETCO2 between these two devices and TC-CO2 and assessed which device is more useful during intravenous sedation in volunteers. Methods: Eight male volunteers aged 25 to 35 years were evaluated in this single-institution blinded observational trial. After they lay quietly for 5 min without supplemental oxygen, the volunteers received supplemental oxygen by means of each device at a flow rate of 3 L/min for 15 min. Next, midazolam (0.05 mg/kg) was intravenously injected, flumazenil (20 mg) was injected 30 min later, and the ETCO2 and TC-CO2 waveform were recorded. Results: The differences between ETCO2 and TC-CO2 significantly increased after midazolam injection and decreased after flumazenil injection. The difference between ETCO2 and TC-CO2 using the nasal cannula was greater than that using the mouth-nose cannula. The mean difference between TC-CO2 and ETCO2 ranged from 3 to 9 mmHg after midazolam injection using a nasal mask, and the mean difference ranged from 3 to 6 mmHg after midazolam injection using a mouth-nose cannula. Conclusions: The difference between ETCO2 and TC-CO2 against TC-CO2 was within the clinically acceptable range. Both the nasal and mouth-nose cannula were useful for ETCO2 measurement with supplemental oxygen by means of each device at flow rate of 3 L/min during intravenous sedation in volunteers.

An application of a reinforced laryngeal mask airway to anesthesia for dental treatment.

tape, and reinforced with a mouth prop in order to keep it in the proper place (Fig. 1A). Pushing the tube with a finger into the oral vestibule and the retrodental space opposite to the treatment site would make it possible to examine and transfer the patient’s occlusion (Fig. 1B). Because of the flexibility of the tube, either dislodgement of the mask part or obstruction of the tube part could occur. Therefore, vigorous monitoring with capnography throughout the treatment will be required. Packing gauze into the pharynx can prevent the dislodgement of the mask part.

Role of pituitary adenylyl cyclase-activating polypeptide in intracellular calcium dynamics of neurons and satellite cells in rat superior cervical ganglia

Pituitary adenylyl cyclase-activating polypeptide (PACAP) is a bioactive peptide with diverse effects in the nervous system. The present study investigated whether stimulation of PACAP receptors (PACAPRs) induces responses in neurons and satellite cells of the superior cervical ganglia (SCG), with special reference to intracellular Ca2+ ([Ca2+]i) changes. The expression of PACAPRs in SCG was detected by reverse transcription-PCR. PACAP type 1 receptor (PAC1R), vasoactive intestinal peptide receptor type (VPAC)1R, and VPAC2R transcripts were expressed in SCG, with PAC1R showing the highest levels. Confocal microscopy analysis revealed that PACAP38 and PACAP27 induced an increase in [Ca2+]i in SCG, first in satellite cells and subsequently in neurons. Neither extracellular Ca2+ removal nor Ca2+ channel blockade affected the PACAP38-induced increase in [Ca2+]i in satellite cells; however, this was partly inhibited in neurons. U73122 or xestospongin C treatment completely and partly abrogated [Ca2+]i changes in satellite cells and in neurons, respectively, whereas VPAC1R and VPAC2R agonists increased [Ca2+]i in satellite cells only. This is the first report demonstrating the expression of PACAPRs specifically, VPAC1 and VPAC2 in SCG and providing evidence for PACAP38-induced [Ca2+]i changes in both satellite cells and neurons via Ca2+ mobilization.

Evaluation of Differences between PaCO2 and ETCO2 by Age as Measured during General Anesthesia with Patients in a Supine Position

Objective. The aim of this study was to evaluate the arterial to end-tidal partial pressure gradient of carbon dioxide according to age in the supine position during general anesthesia. Methods. From January 2001 to December 2013, we evaluated 596 patients aged ≥16 years who underwent general anesthesia in the supine position. The anesthetic charts of these 596 patients, all classified as American Society of Anesthesiologists physical status I or II, were retrospectively reviewed to investigate the accuracy of PaCO2 and ETCO2. Results. The a-ETCO2 was  mmHg for patients aged 16 to <65 years and  mmHg for patients ≥65 years. The a-ETCO2 was  mmHg for patients aged 16 to 25 years,  mmHg for patients aged 26 to 35 years,  mmHg for patients aged 36 to 45 years,  mmHg for patients aged 46 to 55 years,  mmHg for patients aged 56 to 64 years,  mmHg for patients aged 65 to 74 years, and  mmHg for patients aged 75 to 84 years. Conclusion. The arterial to end-tidal partial pressure gradient of carbon dioxide tended to increase with increasing age.

Changes in Intra-cerebral Oxygenation During Intravenous and Inhalational Sedation: A Original Research

Background: Although sedatives such as midazolam or nitrous oxide (N2O) are administered to dental patients, the effects of these drugs on intra-cerebral oxygenation are not well-known. Aims: We investigated the effects of intravenous midazolam or inhalational N2O on intra-cerebral oxygenation using near-infrared spectroscopy. Setting and Design: University hospital, prospective. Materials and Methods: During intravenous sedation, volunteers received supplemental oxygen through nasal cannula at 3 L/min for 10 min (control group). Midazolam (0.05 mg/kg) was then injected intravenously with flumazenil (20 mg) injected 30 min later. In the inhalational sedation study, volunteers lay quietly for 10 min receiving 100% oxygen, then received N2O via nasal mask at concentrations of 10%, 20%, and 25% for 5 min; 30% for 20 min; and supplemental oxygen at 100% for 15 min after N2O was discontinued. Statistical Analysis: Intra-group comparisons were made using one-way analysis of variance for repeated measures followed by Dunnett’s test for multiple comparisons. Differences were considered statistically significant at P < 0.05. Results: During intravenous sedation, oxyhemoglobin increased 10 min after midazolam administration, and total hemoglobin increased slightly until 20 min after flumazenil administration, followed by a decrease. During inhalational sedation, oxyhemoglobin increased until 5 min after starting N2O, and total hemoglobin increased until 5 min after starting N2O, followed by a decrease. Conclusions: Midazolam and N2O influenced intra-cerebral oxygenation during intravenous or inhalational sedation. Cerebral blood flow increased with intravenous sedation when midazolam was administered once at a dose of 0.05 mg/kg and with inhalational sedation when N2O was supplied at a concentration of 25-30%.

Changes in Intra-cerebral Environment in Patients Undergoing Tracheotomy: An Original Research

Background and Objectives: Microvascular flap reconstruction has recently proven to be very reliable for repairing defects in the oral and maxillofacial cavity defects. Such patients often require a tracheotomy to stay in the intensive care unit post-operatively. Although tracheotomy is usually performed after oral intubation, details of the intra-cerebral oxygenation environment during tracheotomy are unclear. Using near-infrared spectroscopy, we investigated the changes in intra-cerebral oxygenation during exchange from oral to tracheal intubation in patients undergoing tracheotomy. Materials and Methods: We evaluated eight patients with an American Society of Anesthesiologists physical Status of I or II who were scheduled to undergo tracheotomy. Changes in the intra-cerebral levels of oxyhemoglobin (oxy-Hb), deoxyhemoglobin (deoxy-Hb), total hemoglobin (total-Hb), and cytochrome oxidase (cyt) were monitored during tracheotomy. Results: Blood pressure increased rapidly during exchange from an oral to tracheal intubation tube. The maximum oxy-Hb level (3.5 ± 2.4 nmol/L) occurred 5 min after the exchange, the maximum deoxy-Hb level (0.8 ± 1.0 nmol/L) occurred 5 min after the exchange, the maximum total-Hb level (1.8 ± 2.2 nmol/L) occurred 5 min after the exchange, and the minimum cyt level (−0.5 ± 0.2 nmol/L) occurred 7 min after the start of the operation. Conclusions: The intra-cerebral oxy-Hb and total-Hb levels increased after exchange from an oral to tracheal intubation tube during tracheotomy, and these hemodynamic changes attenuated the cerebral blood flow.

Severe Bradycardia Possibly due to a Local Anesthetic Oral Mucosal Injection during General Anesthesia

Local anesthesia may induce systemic complications leading to parasympathetic activity leading to bradycardia and hypotension. We report a case of a 50-year-old man undergoing dental surgery under general anesthesia who experienced severe bradycardia and hypotension after local anesthesia infiltration. Concerns regarding the utilization of a relatively large lumen injection needle for local anesthesia during general anesthesia are discussed.